Hypertension is associated with reduced medial temporal lobe neural flexibility in older African Americans

Abstract

AbstractBackgroundHypertension disproportionately affects African Americans (AA) and is an established mid‐life risk factor for Alzheimer’s disease (AD). However, previous research suggests there is inconclusive data examining late‐life hypertension and Alzheimer’s risk. Recently, a dynamic rearrangement (neural flexibility) imaging method was validated for evaluating cognitive decline in the medial temporal lobe (MTL), which is a key region affected by AD. But whether hypertension mediates MTL neural flexibility in older AA individuals is unknown. Therefore, we investigated MTL flexibility in older hypertensive and normotensive AA.MethodOne hundred and thirteen AA (60‐74y) completed demographic surveys, weight and height measurements, resting blood pressure (BP) screening procedure, and a 6‐minute walking distance test as an indirect measure of aerobic capacity. All individuals also completed a 10‐minute resting‐state functional magnetic resonance screening to assess MTL neural flexibility. Participants were separated into normotensive (systolic BP < 130mmHg, n = 36, 83% female, 64.8 ± 0.4y; 13.8 ± 0.2y of education) vs. hypertensive (systolic BP ³ 130mmHg, n = 77, 82% female, 66.4 ± 0.3y; 14.1 ± 0.1y of education). An ANCOVA was used to examine group differences in MTL neural flexibility with age, sex, and education used as covariates.ResultAlthough individuals with hypertension had a higher BMI (36.9 ± 1.8 vs. 31.3 ± 2.6 kg/m2, p = .070), this was not statistically different. However, normotensive participants had significantly higher MTL neural flexibility compared to hypertensive individuals (.42 ± .23 vs. .32 ± .25, p = .04), and this was independent of estimated aerobic capacity (14.9 ± 2.3 vs. 14.9 ± 2.5 ml/kg/min; ml/kg/min; p = .864).ConclusionHypertensive AA between the ages 60‐74 years old demonstrated lower MTL neural flexibility compared to their normotensive counterparts. These results were independent of obesity and aerobic fitness, suggesting additional work is needed to understand how blood pressure mediates neuronal connectivity to prevent and/or treat AD cognitive decline in AA.